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Soil erosion by water is a major environmental problem in the Mediterranean areas. It results in land degradation and soil losses, decreases soil structural stability, and increases soil erodibility. Hence, the need for reliable scientific methods for obtaining soil erosion data becomes crucial. The study aims to estimate soil loss in the Moroccan watershed using two soil erosion estimation models and to discuss the differences between those models. The first model used in this study is the improved tillage homogenization model (T-H) which permits to predict the magnetic susceptibility values after erosion, the second one is the empirical model based on the Revised Universal Soil Loss Equation RUSLE. The results showed that: i) higher soil losses using tillage homogenization (T-H) model have occurred in the upper and lower slopes in the cultivated transect, and in the middleslopes and lower slopes in the forested transect; ii) the average of annual soil loss obtained by RUSLE model is about 20.21 t/ha/yr; iii) T-H model allows us to estimate the total cumulative soil erosion during the past and, while RUSLE model is designed for predicting annual soil loss resulting from sheet erosion under given conditions. [ABSTRACT FROM AUTHOR]

Magnetic susceptibility measurements at low and high frequencies (χlf, χhf) were carried out on topsoil samples from reforested, cultivated, and pasture lands from a catchment located at the north of Morocco. The aims of this study were to investigate the impact of land use or human activity on χlf of soil overlying the same substrate, to discriminate allochthonous material or pollution from autochthonous or inherited ones, and to assess the origin and contribution of superparamagnetic (SP) grains to the global magnetic susceptibility χlf. Measurements of χlf indicated significant enhancement, with values ranging from 12.4 to 252.82 × 10-8 m3 kg−1 with a mean value of 107.087 × 10-8 m3 kg−1 for the reforested lands. In the cultivated lands, χlf were from 8.4 to 88.65 × 10-8 m3 kg1 with a mean value of 42.69 × 10-8 m3 kg−1, while in the pasture lands, χlf was comprised between 14.34 × 10-8 m3 kg−1 and 133.35 × 10-8 m3 kg−1 with a mean value of 57.33 × 10-8 m3 kg−1. The magnetic enhancement indicates high concentration of ferrimagnetic minerals in the top soil. The magnetic susceptibility enhancement decreases as the human activity increases, while the underlying bedrock is almost the same: reforested land > pastures land > cultivated land. The analysis of the variations of χlf and frequency dependent susceptibilities (χfd and %χfd), along the profiles of soil, indicate a pedogenic origin of the topsoil magnetic susceptibility enhancement. [ABSTRACT FROM AUTHOR]

The article assesses the soil degradation in the Eastern Rif, Morocco using magnetic susceptibility. The variation of magnetic susceptibility in the soil profile is related to the differences in the original magnetic composition and the influence of main erosion factors. The main factor that contributes to this variation is lithology. Slope affects the distribution of magnetic susceptibility in the soil.